Vegetable oil derivatives as extender oils for elastomer compositions

ABSTRACT

Elastomer composition comprising at least one elastomer and at least one vegetable oil derivative selected from one or more of: a. mixture of triglycerides comprising one or more of the following oligomeric structures: R 4 [OC(O)R 1 C(O)OCH 2 CH(OR 2 )CH 2 ] n OR 3  and said mixture of triglycerides having a Numerical Average Molecular Weight (Mn) of between 800 and 10,000, b. triglycerides of one or more long chain carboxylic acids including at least one carboxylic acid containing adjacent hydroxyl groups, c. esters of polyols with at least a monocarboxylic acid and at least a dicarboxylic acid, the said esters being other than triglycerides.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a National Phase filing under 35 U.S.C. §371 ofPCT/EP2011/073494 filed on Dec. 20, 2011; and this application claimspriority to Application No. MI2010A002325 filed in France on Dec. 20,2010 under 35 U.S.C. §119; the entire contents of all are herebyincorporated by reference.

This invention relates to elastomer compositions containing vegetableoil derivatives as extender oils.

During the processing of both synthetic and natural rubbers it is commonpractice to use extender oils during the compounding stage. These oils,also known as process oils, have an essentially plasticising action andmake it possible to improve the workability of the rubber, reduce mixingtimes, minimise the quantity of heat generated and maximise thedispersion of components, at the same time as increasing the coldelasticity and flexibility of the vulcanised products withoutundesirable effects on the more important physical properties. Also, ifused in significant quantities, such oils extend the volume of theproduct, reducing costs. Typically used as extender oils are mineraloils derived from the processing of petroleum which can be classifiedinto paraffin (aliphatic), naphthenic (cycloaliphatic) and aromaticoils. When processing elastomers, in particular for the manufacture oftyres, aromatic extracts known as DAE (Distillate Aromatic Extracts),which nevertheless contain polycyclic aromatic hydrocarbons (PAC) and inparticular polyaromatic hydrocarbons (PAH), which are considered to becarcinogenic substances, are conventionally used.

A recent European directive (Directive 2005/69/EC) however restricts thepolyaromatic hydrocarbons content (PAH) of extender oils and tyres. Onepossible solution identified is the replacement of aromatic oils witharomatic and paraffinic oils treated to reduce the polycyclics content,known respectively as TDAE (Treated Distillate Aromatic Extracts) andMES (Mild Extraction Solvates).

For example U.S. Pat. No. 6,984,687 (Goodyear) describes an elastomercomposition containing 5 to 70 parts by weight (phr) of an extender oilhaving a glass transition temperature of between −80 and −40° C., anaromatic polycyclics content of less than 3% and a total aromatics whichis in any event less than 20% by weight. Extender oils having a low PACcontent described in this patent are MES and heavy naphthenic oils.

A different solution is represented by the replacement of mineral oilsby oils of natural origin, in particular vegetable oils.

In elastomer formulations it is also common practice to use reinforcingmaterials, such as carbon black or “white” materials. These whitematerials, in particular the silicas, require coupling agents to bepresent in the formulation in order to better perform their function.These coupling agents typically comprise organosilanes.

This invention relates to elastomer compositions containing particularvegetable oil derivatives as extender oils. It has in fact beensurprisingly discovered that it is possible to use the said vegetableoil derivatives as a substitute for conventional extender oils forelastomers, substantially improving some mechanical properties andmaintaining other properties of the elastomer compositions substantiallyunchanged, with significant advantages from the economic profile too.

Some vegetable derivatives according to this invention may also make itpossible to render the elastomers compatible with silicas, reducing oreliminating the use of coupling agents in the formulation.

In particular the object of this invention are elastomer compositionscomprising at least one elastomer and at least one vegetable oilderivative selected from one or more of:

-   -   a. mixture of triglycerides comprising one or more of the        following oligomeric structures:        R₄—[O—C(O)—R₁—C(O)—O—CH₂—CH(OR₂)—CH₂]_(n)—O—R₃        -   wherein            -   R₁ is selected from C₂-C₂₂ alkylenes,            -   R₂ is selected from one or more of the following groups                consisting of C₆-C₂₄ dicarboxylic acid residues and                C₆-C₂₄ monocarboxylic acid residues,            -   R₃ is selected from one or more of the following groups                consisting of H, C₆-C₂₄ dicarboxylic acid residues and                C₆-C₂₄ monocarboxylic acid residues,            -   R₄ is an alkyl group,            -   n is an integer greater than or equal to 2,            -   said C₆-C₂₄ dicarboxylic acid residues of R₂ and R₃                being esterified with monoalcohols and said mixture of                triglycerides having a Numerical Average Molecular                Weight (Mn) of between 800 and 10.000.    -   b. triglycerides of one or more long chain carboxylic acids        including at least one carboxylic acid containing adjacent        hydroxyl groups,    -   c. esters of polyols with at least a C₆-C₂₄ monocarboxylic acid        and at least a C₆-C₂₄ dicarboxylic acid, the said esters being        other than triglycerides.

The invention also relates to vulcanized products obtained from saidelastomeric compositions.

By the term elastomer are meant both natural rubbers (NR) and syntheticrubbers. Examples of synthetic rubbers are diene-based rubbers such asvinylarene-conjugated diene copolymers (e.g. SBR, Styrene/ButadieneRubber), diene polymers (e.g. polybutadiene, polyisoprene),ethylene-propylene copolymers, in particular ethylene/propylene/dieneterpolymers (EPDM, Ethylene/Propylene/Diene Monomer) and thermoplasticelastomers such as styrene-butadiene-styrene (SBS) block copolymers,nitrile rubbers, acrylonitrile-butadiene copolymers (NBR) andstyrene-isoprene-styrene (SIS) polar rubbers.

The said elastomer may be used as such or in a mixture with otherelastomers.

In a preferred embodiment of the invention the elastomer comprisespolydiene rubbers or vinylarene-conjugated diene random copolymers.

Typical examples of vinylarenes are styrene and relative alkylatedcompounds. In a preferred embodiment, the vinylarene is styrene.

The conjugated dienes are 1,3 dienes having from 4 to 12 carbon atoms,preferably from 4 to 8 carbon atoms. Examples of these dienes are1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene(piperylene), 2-methyl-3-ethyl-1,3-butadiene, 1,3-octadiene. In apreferred embodiment, the conjugated diene monomers are selected from1,3-butadiene and isoprene and mixtures thereof, preferably1,3-butadiene.

In the following description, reference will be made to styrene as atypical vinylarene and to butadiene as a typical conjugated diene, butwithout limiting ourselves to these compounds. With the term“styrene-butadiene random copolymer” is meant a styrene-butadienecopolymer wherein the content of styrene in the form of blocks (i.e.sequences of at least 10 styrene units directly linked each other), withrespect to the total content of styrene, is 2% or less, as measuredthrough the oxidative decomposition method described by I. M. Kolthoffet al. in J. Polymer Science, Vol. 1, page 429 (1946), or, morerecently, by Viola et al. (Sequence distribution of styrene-butadienecopolymers by ozonolysis, high performance liquid chromatographic andgas chromatographic-mass spectrometric techniques, J. Chromatography A,117 (1994)).

The above styrene-butadiene random copolymers preferably have a styrenecontent from 15 to 50% by weight, more preferably from 20 to 50% byweight.

As is known, 1,3 dienes can be bound to the polymeric chain as cis-1,4bond (cis bond) trans-1,4 bond (trans bond), 1,2 bond (vinyl unit). Inthe meaning of the present invention, the content of vinyl units isdefined as the ratio between the quantity of vinyl units and the sum ofthe cis, trans and vinyl bonds. The vinyl unit content of the dieneportion of the styrene-butadiene random copolymer is preferably from 10to 80%. The content of vinyl unit can be uniformly distributed along thepolymeric chain, or it can be incremented or diminished along the chainitself.

The styrene-butadiene random elastomeric copolymer can be obtained bytwo different processes: from solution or as emulsion.

As far as solution processes are concerned, they are preferablyperformed by anionic polymerization initiated by lithium alkyls inhydrocarbon solvents. In this case the weight average molecular weight(Mw) measured by means of exclusion chromatography is between 50,000 and1,000,000. The dispersion index value (Mw/Mn) is between 1 and 10.Preferably Mw is between 300,000 and 800,000 and Mw/Mn is between 1 and5, more preferably between 1 and 3. The styrene-butadiene copolymershave a styrene content from 15 to 50% by weight, preferably of 20 to 45%by weight. The vinyl unit content is preferably from 10 to 80% byweight, even more preferably from 20 to 70%. The molecular structure islinear or branched, the latter being obtained by reacting the activeterminals at the end of the polymerization with coupling agents such assilicon tetrachloride, tin tetrachloride, or other multi-functionalcoupling agents according to the known art. The Mooney viscosity of thenon-oil-extended polymer M_(L)(1+4) @ 100° C. is from 30 to 200 MooneyUnits (MU), preferably from 50 to 150, whereas the corresponding polymerextended with extender oils according to the invention has a Mooneyviscosity at 100° C. within the range of 30-120 MU. As far as emulsionprocesses are concerned, they are preferably performed by radicalicpolymerization. In this case, a branched structure is obtained due tomolecular chain transfer reactions during the propagation step. Theamount of styrene is preferably between 20 and 50% by weight, while theamount of vinyl units is between 15 and 25% depending on the temperatureduring the synthesis reaction. The polymer extended with extender oilsaccording to the invention has a Mooney viscosity at 100° C. between30-120.

The vegetable oils derivatives according to this invention arecharacterised by relatively low molecular weight. Preferably the averagemolecular weight is less than 10000 g/mol. The said vegetable oilderivatives are also characterised by high stability to thermaloxidation and high stability to hydrolysis.

With reference to group a) of vegetable oil derivatives according tothis invention, it is preferred that R₁ is a C₆-C₁₁ alkylene, C₆, C₇and/or C₁₁ alkylene being particularly preferred.

The two or more R₁ in the structure can be different from each other.

R₂ represents C₆-C₂₄ dicarboxylic acid residues or C₆-C₂₄ monocarboxylicacid residues or a mixture thereof. The two or more R₂ in the structurecan be different from each other.

R₃ represents a C₆-C₂₄ dicarboxylic acid residue or a C₆-C₂₄monocarboxylic acid residue.

When R₂ and/or R₃ represents C₆-C₂₄ dicarboxylic acid residues, the freeacid groups of C₆-C₂₄ dicarboxylic acid residues are esterified withlinear or branched C₁-C₁₂ monoalcohols. Short chain alcohols such as forexample methyl alcohol, ethyl alcohol, propyl alcohol and butyl alcoholare particularly preferred. Ethyl alcohol and butyl alcohol areparticularly advantageous.

R₄ is preferably a linear or branched C₁-C₁₂ alkyl group, morepreferably a C₂ or a C₄ alkyl group.

For the group a) of vegetable oil derivatives, by C₆-C₂₄ dicarboxylicacids are meant aliphatic diacids, preferably of the alpha-omega type.Suberic acid, azelaic acid and brassylic acids and their mixtures areparticularly preferred.

For the group a) of vegetable oil derivatives, by C₆-C₂₄ monocarboxylicacid are meant monoacids possibly having one or more unsaturations alongthe chain and being unsubstituted or substituted.

Preferred unsubstituted monocarboxylic acids are mono acids having achain length of C₉₋₂₄, palmitic, stearic, oleic, arachic, behenic andlignoceric acids being particularly preferred.

With reference to substituted monocarboxylic acids, long chainmonocarboxylic acids with one or more keto groups or hydroxyl groups ina non-terminal position are preferred, among these C₁₂-C₂₄ carboxylicacids containing at least a ketone group or C₁₂-C₂₄ hydroxy acidscontaining at least one secondary hydroxyl group are particularlypreferred. Examples of preferred substituted monocarboxylic acids are9-hydroxystearic acid, 9-ketostearic acid, 10-ketostearic acid and10-hydroxystearic acid.

Said substituted monocarboxylic acids may have two adjacent hydroxylgroups or an hydroxyl group adjacent to a keto group. If two adjacenthydroxyl groups are present, dihydroxypalmitic, dihydroxystearic,dihydroxyoleic, dihydroxyarachic and dihydroxybehenic acids arepreferred. 9,10-dihydroxystearic acid is particularly preferred.Advantageously, the group a) of vegetable oil derivatives are dimer ortrimer esters of triglycerides having a number of repeating units (n)equal to 2 or equal to 3.

Particularly preferred are dimer and trimer esters of triglyceridescontaining C₆-C₂₄ dicarboxylic acid residues. Example of preferred dimerand trimer esters are represented by the following structures:

Other examples of oligomeric structures have R₁=C₇ alkylene, R₄=C₄ alkyland n=2 and R₂ and R₃ independently selected from the following groups:—C(O)—(CH₂)₆₋₁₀—COOBu—C(O)—(CH₂)₁₆—COOBu—C(O)—(CH₂)₆₋₁₀CH₃—C(O)—(CH₂)₁₆—CH₃—C(O)—(CH₂)₈₋₉—CO—(CH₂)₇₋₈—CH₃C(O)—(CH₂)₆—CO—(CH₂)₇—CH═CH—CH₃.

The group a) of vegetable oil derivatives may possibly contain monomerictriglycerides containing at least a C₆-C₂₄ dicarboxylic acid residue.Monomeric triglycerides containing two C₆-C₂₄ dicarboxylic acidsresidues, said dicarboxylic acids being the same or different, areparticularly preferred. Also preferred are monomeric triglyceridescontaining at least a C₆-C₂₄ dicarboxylic acids residue and at least aC₆-C₂₄ monocarboxylic acids residue having at least a keto group and/orat least an hydroxyl group.

Preferably, the group a) of vegetable oil derivatives further containsoligoglycerols such as diglycerol and triglycerol and their esters withmono- or dicarboxylic acids. Preferred are esters of diglycerols andtriglycerols comprising one or more C₆-C₂₄ dicarboxylic acids. Alsopreferred are esters of diglycerols and triglycerols comprising at leasta saturated or unsaturated monocarboxylic acid containing one or morehydroxyl group and/or a keto group. The mixture of triglyceridescomprising one or more oligomeric structures of group a) of vegetableoil derivatives preferably has a Mn between 800 and 10000 Da, akinematic viscosity at 100° C. between 5 and 400 cSt and a Tg between−85° C. and −40° C., preferably between −80° C. and −50° C. and morepreferably between −78° C. and −60° C.

Numerical Average Molecular Weight (Mn) is determined by GPC analysisfollowing prior calibration with polystyrene standards.

Kinematic viscosity is calculated as the ratio of dynamic viscosity(measured with a HAAKE VT 500 rotational viscosimeter provided with MV1rotor at 100° C.) and density.

Tg is determined by Differential Scanning calorimetry with a single runstarting from −100° C. up to 30° C. at a temperature speed of 20°C./min.

Said mixture of triglycerides preferably have a density, determined byweighing 100 mL of said mixture at 100° C., between 0.90 and 1.05 g/cm³(T=100° C.).

Advantageously, the acid number of said mixture is below 50, preferablybelow 10 and more preferably below 5 mg KOH/g. By acid number is meantthe quantity of KOH expressed in mg used to neutralise the acidity of 1g of substance. The determination is performed according to standardASTM D974-07 in the presence of phenolphthalein.

The degree of unsaturation of said mixture, expressed by the I₂ numberand determined by titration according to the Wijs method, is preferablybetween 0 and 140 g I₂/100 g.

The saponification number of the triglycerides mixture, understood to bethe quantity of KOH expressed in mg consumed in the saponification of 1gram of substance, is preferably between 150 and 500 mg KOH/g. It isdetermined by titration with HCl, in the presence of phenolphthalein, ofthe residual KOH after reflux saponification for 60 minutes.

The hydroxyl number of the triglycerides mixture is preferably between10 and 100 mg KOH/g.

The mixture of triglycerides is insoluble in boiling water. Said mixtureis however completely soluble in diethylether, ethyl alcohol, acetoneand chloroform at ambient temperature. It is also characterised by highstability to hydrolysis.

The mixture of triglycerides comprising one or more oligomericstructures of group a) of vegetable oil derivatives can be prepared asdisclosed in the Italian patent application MI2010A002324 and in theInternational patent application having title “Complex oligomericstructures” (PCT/EP2011/073492) claiming its priority, the content ofsaid patent applications being herein incorporated by reference.

With reference to group b) of vegetable oil derivatives according tothis invention (triglycerides of one or more long-chain carboxylic acidsof which at least one carboxylic acid contains adjacent hydroxylgroups), the product of the partial or total oxidation of vegetable oilswith H₂O₂ is particularly preferred. By way of example, the derivativesobtained according to the processes described in patent applicationsWO/2008138892 and MI2009A002360 are considered. Derivatives of sunflowerand in particular sunflower oil having a high oleic acid content (HOSO)are of particular interest.

With reference to group c) of vegetable oil derivatives according tothis invention (esters, other than triglycerides, of polyols with atleast a monocarboxylic acid and at least a dicarboxylic acid), bypolyols are meant alcohols containing at least two hydroxyl groups.Particularly preferred are polyols such as neopentylglycol,trimethylpropane and pentaerythritol, and in any event polyolscontaining only primary hydroxyl groups. Advantageously the said esterscontain monocarboxylic and dicarboxylic acids in ratios of preferablybetween 2:1 and 10:1. Preferably the monocarboxylic acids have C₈-C₂₄chains; the dicarboxylic acids have C₆-C₂₄ chains.

The vegetable oil derivatives according to this invention may be used asextender oils for elastomers as such or in a mixture with mineral and/ornatural oils. Said mixtures preferably contain 15-45% by weight ofvegetable oil derivatives. The mineral oil in the mixture can be of theparaffin, naphthene or aromatic type and relative mixtures. Examples ofmineral oils are DAE, TDAE, MES and RAE (residual aromatic extract). Bynatural oils are meant all oils not derived from petroleum, of animalorigin (for example whale oil and fish oil) and of plant origin.

Among natural oils vegetable oils such as for example peanut oils,Brassicaceae oils, hemp oils, safflower oils, coconut oils, sunfloweroils with a various oleic content, jatropha oils, linseed oils, oliveoils, macadamia oils, mahua oils, neem oils, palm oils, poppy oils,pongamia oils, castor oils, rice oils, rubber tree seed oils (Heveabrasiliensis), maize seed oils, mustard oils, sesame oils and grape seedoils are preferred.

The extender oils may be present in the elastomeric composition in aquantity ranging from 5 to 75 parts of oil per 100 parts of rubber,preferably from 7 to 50 and even more preferably from 10 to 40 parts ofoil per 100 parts of rubber.

According to one embodiment of the present invention, the extender oilis added during the industrial preparation of the elastomer. Forexample, in the case of elastomeric copolymers obtained by solutionanionic polymerization, the extender oil can be fed in the polymersolution, preferably followed by additives such as antioxidants.Advantageously, at the end of the solution anionic polymerization thesolvent is removed by steam in a steam agitated and heated bath. In thecase of elastomeric copolymers obtained by radical polymerization,extender oils can be advantageously fed in the water emulsion,preferably followed by additives as usual and by the removal of solventafter coagulation due to addition of sulphuric acid. The rubber is thendried using either mechanical press or drying ovens and finally formedinto bales.

According to another embodiment, the extender oil is added during thecompounding stage. In addition to extender oil, fillers, vulcanisationagents (e.g. sulphur) and vulcanisation accelerators, activators andretardants, organic acids, antioxidants, reinforcing materials, processcoadjuvants and other additives may be added to the elastomer, as knownin the art. Examples of fillers included in the elastomer composition towhich this invention relates are kaolin, barytes, calcium carbonate,clay, talc, aluminium hydroxide, diatomaceous earth, aluminium sulphate,barium sulphate and magnesium, iron and lead carbonates. Examples ofreinforcing materials are carbon black, silicas, activated calciumcarbonate or organic compounds such as resins with a high styrenecontent and phenol-formaldehyde resins.

Biofillers from renewable sources such as for example the starch-basedcomplexes described in Patent EP 1127089 B1 may also be used as fillers.

With respect to carbon black, the normal carbon black used forreinforcing elastomers can be used in a quantity ranging from 10 to 150phr, preferably from 10 to 100 phr, even more preferably from 15 to 80phr. In a preferred embodiment, the carbon black has a specific surfacearea, determined by means of nitrogen absorption ranging from 40 to 200m2/g and a DBP (dibutyl phthalate) absorption number, determinedaccording to ASTM-D-2414 ranging from 70 to 180 ml/100 g. The carbonblack is preferably in the form of small particles having a good oilabsorption capacity. Even more preferably a carbon black in which —OHgroups have been introduced in the surface is used, as these groups arereactive with respect to the organosilane coupling agents.

Any type of silica can be used, for example anhydrous silica obtained byprecipitation from sodium silicate, with a dimension ranging from 20 to80 nm, a surface area of 35-250 m2/g. The quantity of silica is usuallywithin the range of 10 to 150 phr, preferably from 15 to 120 phr.

If silicas are used, common coupling agents, typically comprisingorganosilanes, will be added to the elastomer compositions according tothe invention. A typical organosilane is a functionalizedtrialkoxysilane or dialkoxysilane. In a preferred embodiment,organosilane has one of the three general formulae (d, e, f) indicatedhereunder:(RO)₃SiC_(n)H_(2n)S_(m)C_(n)H_(2n)Si(OR)₃  (d)(RO)₃SiC_(n)H_(2n)X  (e)(RO)₃SiC_(n)H_(2n)S_(m)Y  (f)wherein R represents an alkyl group having from 1 to 4 carbon atoms, thethree Rs being the same or different; “n” represents an integer from 1to 6, “m” represents an integer from 1 to 6; X represents a mercaptangroup, an amine group, a vinyl group, a nitrous group, an imido group, achlorine atom or epoxy group;

Y represents a cyano group, a N,N-dimethylthiocarbamoyl group, amercaptobenzotriazole group, or a methacrylate group.

Organo-silanes having at least one sulphur atom are preferred, for theirreactivity towards the rubber in the vulcanization phase. In particularorgano-silanes selected from bis(3-triethoxysilylpropyl)tetrasulphide;γ-mercaptopropyl methoxysilane,-3-thiocyanatepropyl triethoxysilane;trimethoxysilyl propyl mercaptbenzotriazole tetrasulphide, arepreferred. The coupling agent is used in quantity usually up to 20 phr.

It should be pointed out that silica and the coupling agent, can besubstituted by a compound deriving from the reaction of silane withsilica. In other words, the elastomeric composition of the presentinvention can contain, in partial or total substitution of the silicaand silane, the reaction product between silane and silica.

The coupling agents have the function of stabilising a bond of achemical or physical nature between the elastomer and the reinforcingmaterial, assisting dispersion of the latter and ensuring goodmechanical properties for the elastomer compositions.

Surprisingly, it has been found that the elastomer compositionsaccording to this invention containing derivative (c) as extender oiland reinforced with silica maintain good mechanical properties even inthe absence of common coupling agents. This makes it possible to avoidthe costs associated with silanes, making the use of vegetable oilderivatives according to the invention in elastomer compositions evenmore advantageous.

As far as vulcanizing agents are concerned, these are sulphur or acompound containing sulphur. Typical compounds containing sulphur aresulphur monochloride, sulphur dichloride, a disulphide, a polysulphide.The preferred vulcanizing compound is sulphur. The quantity ofvulcanizing agent ranges from 0.1 to 10 phr. A vulcanizationaccelerator, an activator and a crosslinking agent can also be usedtogether with the vulcanizing agent. The vulcanization acceleratorsinclude derivatives of guanidine, amino-aldehydes, ammonia-aldehydes,derivatives of thiazole, amido-sulphene compounds, thioureas, thiouram,dithiocarbamates, xanthates. Typical activators are zinc oxide andStearic acid.

Typical examples of crosslinking agents comprise oxime derivatives,nitrous derivatives, polyamines, in addition to a radicalic initiatorsuch as an organic peroxide and an azo-derivative.

Examples of antioxidants or anti-aging agents are derivatives of aminessuch as diphenylamine and p-phenylenediamine, derivatives of quinolineand hydro-quinone, monophenols, diphenols, thiobisphenols, hinderedphenols, esters of phosphoric acid. These compounds, and relativemixtures, can be used within the range of 0.001 to 10 parts by weightper 100 parts of elastomeric material.

The elastomer composition according to the invention may be subsequentlymixed, shaped and vulcanised according to known methods.

The elastomer composition containing vegetable oil derivatives accordingto this invention finds use in particular in the manufacture of tyres.

In this connection, a particularly preferred embodiment of the presentinvention relates to a raw elastomeric composition comprising:

(A1) from 30 to 100% by weight of a vinylarene-conjugated diene randomelastomeric copolymer;

(A2) from 0 to 70% by weight, preferably from 0 to 40% by weight of oneor more diene rubbers,

the total amount of elastomers (A1)+(A2) being equal to 100, and

(B) from 10 to 150 phr, preferably from 15 to 120 phr of silica orcarbon black or mixtures thereof;

(C) from 10 to 100 phr, preferably from 20 to 60 phr of a vegetable oilderivative according to the present invention or their mixtures withother mineral and/or natural oils;

(D) from 0.1 to 20 phr of a coupling agent based on silane;

(E) from 0.1 to 10 phr of a vulcanizing agent.

As far as (A1) is concerned, it can be obtained either by anionicpolymerization initiated by lithium alkyls in hydrocarbon solvents or byradicalic polymerization in emulsion. Advantageously thevinylarene-conjugated diene random elastomeric copolymers are styrenebutadiene copolymers.

The component (A2), i.e. the diene rubber, is an elastomer selected fromthe group comprising natural rubber, polybutadiene, polyisoprene,styrene-butadiene copolymer, styrene-isoprene copolymer,isoprene-butadiene copolymer. If polybutadiene is used as component(A2), it is preferably selected from polybutadiene cis-1,4 and highvinyl polybutadiene (vinyl content from 40 to 90%) and relative blends.When component (A2) is polyisoprene, it is preferably a polyisoprenecis-1,4 with a cis-1,4 percentage higher than 90% by weight. Thecomponent A2 can also consist of mixtures in any proportion of syntheticpolyisoprene or natural rubber with polybutadiene with high (>90%)content of 1,4-cis units. The component (C) preferably belongs to groupa) of vegetable oil derivatives according to the present invention(mixture of triglycerides comprising oligomeric structures).

The above raw elastomeric composition can be prepared by mixingcomponents (A)-(E), and the formulation agents, using the typicalequipment adopted for the mixing of elastomeric compounds, for exampleroll mixers, a Banbury internal mixer, extruders. The mixture is thenformed and vulcanized. The mixing of the ingredients can be effected ina single step or in various passages. In this latter case, a firstmethod consists of first mixing the elastomeric components (A1) and(A2), optionally already containing the extender oil (C), the silicaand/or carbon black (B) and the coupling agent (D) and other additivesin an internal mixer of the Banbury type and subsequently thevulcanizing agent (E) and accelerators in a roll mixer. In anothermethod the silica and coupling agent are first mixed and reacted and theproduct of this reaction is subsequently mixed with the elastomers (A1)and (A2) and finally with the vulcanizing agent.

The present invention also encompasses, in general, rubber compounds(i.e. vulcanized products) prepared from the elastomeric compositionsabove disclosed.

The vulcanized products according to the present invention, particularlythose containing vinylarene-conjugated diene random elastomericcopolymers and polydiene with a high cis units content, appear to beparticularly suitable as tyre tread, especially for cars, due to theirexcellent adhesion to wet surfaces or on ice while presenting a lowrolling resistance. Since the wet grip properties—or otherwise sealingproperties under poor grip conditions—are usually achieved to thedetriment of rolling resistance, this represents an unexpectedadvantage.

For example, is known that an increase in the styrene fraction ofcopolymers leads to increased hysteresis of the rubber with the resultof an increase in adherence, but a worsening of the rolling resistanceproperties.

Surprisingly, it has been found that elastomeric compositions comprisingstyrene-butadiene random copolymers, particularly those having a highstyrene content, and a vegetable oil derivative as extender oilaccording to the present invention allows to obtain vulcanized productswith increased wet grip properties and reduced rolling resistance indexwith respect to elastomeric composition containing traditional extenderoils.

The elastomeric compositions according to the invention will now bedescribed by way of non-limiting examples. The examples given below areintended to highlight the benefits arising from the use of vegetable oilderivatives according to the present invention.

EXAMPLES Examples 1-5

The dynamic-mechanical properties of elastomer compositions containingvegetable oil derivatives according to the invention (Examples 1-3) werecompared with those of elastomer compositions containing extender oilsderived from petroleum with a low PAC content (TDAE, Example 4) andvegetable oils as such (Example 5).

The vegetable oil derivative used in Example 1 was a sunflower oilderivative belonging to group a). For its preparation, a mixture oftriglycerides containing saturated carboxylic acids having more than oneacid function was obtained from the organic phase after the hydrolysisstep d) at the end of the oxidative cleavage process described in thepatent application MI2009A002360. The free carboxylic acids contained inthe organic phase were evaporated in a thin film evaporator operating ata pressure of 5 mbar, with a temperature of diathermic oil of 270° C.and with the following operative conditions:

Temperature of the feeding=105° C.

Temperature of the vapour phase=205° C.

Temperature of the reaction residue=250° C.

Said mixture of triglycerides containing saturated carboxylic acidshaving more than one acid function was esterified with ethyl alcohol.The esterification reaction with ethyl alcohol, catalysed by sulphuricacid, was performed in toluene heating the reaction to reflux andremoving the water formed in the course of the reaction by azeotropicdistillation. The ester was purified by dilution with ether andsuccessive washings with distilled water and aqueous sodium bicarbonatesolution to remove the acid catalyst; the excess ethanol and volatileethyl esters were then separated out by evaporation under vacuum(pressure=0.1 mbar, temperature of vapours between 60-160° C.).

TABLE 1 Example Extender oil 1 Mixture of triglycerides containingoligomeric structures esterified with ethanol (derivative a.) 2Triglyceride containing 80% of 9,10-dihydroxystearic acid (derivativeb.) 3 Bis[di(hydroxymethyl)-2,2-butanol-1] azelate tetrapelargonate(derivative c.) Comparison-4 TDAE Comparison-5 HOSO sunflower oil (82%oleic acid, 10% linoleic acid, 4.5% palmitic acid, 3.5% stearic acid).

Five identical elastomer compositions containing SBR as the baseelastomer were prepared. These compositions differ only in the compoundused as extender oil (Table 1).

Table 2 shows the quantities by weight in the elastomer compositionscontaining the extender oils in Table 1, specifying the quantities ofthe individual ingredients in relation to one hundred parts of rubber(phr).

TABLE 2 Quantities by weight in the elastomer composition Material phrSBR 1502 100.0 Precipitated silica (Zeosil 1165 MP) 60.0 Extender oil17.0 Silane (TESPT) 4.8 Preservative (TMQ) 1.5 Activator (ZnO) 2.6Vulcanisers (sulphur, MBTS, TBBS) 3.8

The components were dispersed in the rubber using a BanburyPomini-Farrel model PLO4 mixer. After loading the rubber a 30 sec stageof mastication at a temperature of 125° C. was initiated, at a rate of60 rpm.

First ⅓ of the silica and ⅓ of the extender oil were added, allowingthem to mix for 30 sec, and then ⅓ of the silica, ⅓ of the oil and thesilane were added, mixing for a further 30 sec. The remainder of thesilica, oil and preservative were successively added to the mixer,mixing for a further 30 sec.

Mixing was then continued for a maximum time of 7 minutes, in any eventstopping the process at 160° C.

The mixture was discharged, cooled and reloaded into the mixer at atemperature of 140° C., mixing being continued at 60 rpm for a maximumtime of 10 minutes, in any event stopping the process at 160° C.

The mixture was discharged and allowed to cool, and then again placedback in the mixer at 55° C. The activator and the vulcanisers were addedand allowed to mix for 2 minutes at 60 rpm.

The mixture so obtained was vulcanised in a press at 160° C. for 10minutes to prepare the test specimens intended for mechanicalcharacterization.

Tensile tests in particular were performed, measuring the UltimateTensile Strength (σ_(b)), the Elongation corresponding to the UltimateTensile Strength (ε_(b)) and Elastic Modulus with reference to anelongation of 200% (E_(200%)) according to standard ASTM D412. Reboundwas also tested according to standard ASTM D7121 and Shore A Hardnessaccording to standard ASTM D2240.

As may be seen from the data shown in Table 3, all the elastomercompositions show substantially comparable Rebound and Shore Hardnessproperties, while the elastomer compositions according to the invention(Examples 1, 2 and 3) have a better Ultimate Tensile Strength andElastic Modulus than the reference compositions containing TDAE and HOSOas extender oil (comparison Examples 4 and 5).

TABLE 3 Mechanical properties of the elastomer compositions Reboundσ_(b) ε_(b) E_((200%)) resilience Examples (MPa) (%) (MPa) (%) Shore A 112.2 374 2.7 36.2 38 2 13.5 391 2.7 36.1 62 3 15 330 3.4 36.1 39Comparison-4 8.0 388 1.7 36.1 43 Comparison-5 10.5 433 1.5 36.0 30

This fact indicates a better degree of vulcanisation associated with anincrease in compatibility between the extender oil according to theinvention and the rubber. This makes it possible to use high quantitiesof extender oil in the mixture. Extension of the volume makes itpossible to reduce the costs associated with the production of mixturesbut also to vary properties according to the needs of specificapplications.

The mixtures so obtained are particularly suitable for the manufactureof tyre treads.

Examples 6-8

Two elastomer compositions containing a derivative (c) according to theinvention were prepared in the presence and absence of silane (Examples6 and 7 respectively) and compared with an elastomer compositioncontaining a conventional extender oil prepared without silane(comparison Example 8).

The mixtures, with the ratios indicated in Table 2, were prepared usingthe process indicated in the previous examples.

The compositions in Examples 6 and 7 contained derivative (c.) accordingto the invention in a mixture with TDAE mineral oil. The correspondingproportions by weight are shown in Table 4.

In Comparison Example 8 only TDAE was used as extender oil; theelastomer composition in Example 8 without silane can therefore becompared with that in Example 4 prepared with silane.

TABLE 4 Example Extender oil Silane 6 72% TDAE Yes 28%bis[di-hydroxymethyl]-2,2-butanol-1] azelate tetrapelargonate 7 72% TDAENo 28% bis[di-hydroxymethyl]-2,2-butanol-1] azelate tetrapelargonateComparison-8 100% TDAE No

Each of the compositions were vulcanised and shaped into test specimensin accordance with the procedure described for Examples 1-5.

The dynamic-mechanical properties of these elastomer compositions in thepresence and absence of silane with a coupling agent were then compared.

TABLE 5 Mechanical properties of the elastomer compositions σ_(b) ε_(b)E_((200%)) Examples (MPa) (%) (MPa) Shore A 6 8.5 346 2.1 45 (silane) 78.1 561 1.7 51 (no silane) Comparison-4 8.0 388 1.7 43 (silane)Comparison-8 3.0 286 1.2 38 (no silane)

Looking at the data in Table 5 it will be noted that the elastomercomposition according to the invention, containing a type (c.)derivative and prepared in the absence of silane (Example 7), keepssubstantially unchanged mechanical properties in comparison with anidentical composition prepared in the presence of silane (Example 6).

The comparison composition prepared by TDAE in the absence of silane(Example 8) instead has an Ultimate Tensile Strength and Elastic Moduluswhich are decidedly poorer than those of Example 4 containing silane.

This indicates that the extender oil according to the invention has acompatibilising effect in relation to the reinforcing filler. Theresulting elastomer composition does not therefore require the additionof coupling agents.

Examples 9-20

In the following examples, different oil extended elastomericcompositions particularly suitable for use in the construction of tyretreads are compared.

Rubber compounds with similar glass transition temperatures (measured byDMA) based on different elastomeric compositions have been prepared inorder to evaluate the tyre tread performances, with particular referenceto the predictors for wet grip (WG) and rolling resistance (RR).

The elastomeric compositions used in the evaluation of said rubbercompounds have been prepared from base elastomers with different styreneand vinyl content.

The vegetable oil derivative of the group a) used as extender oil in thefollowing examples according to the invention was prepared from the samemixture of triglycerides containing saturated carboxylic acids havingmore than one acid function prepared in Example 1 and then esterifiedwith butyl alcohol. The esterification reaction with butyl alcohol,catalysed by sulphuric acid, was performed heating the reaction toreflux and removing the water formed in the course of the reaction byazeotropic distillation. The product was purified by washings withdistilled water and aqueous sodium bicarbonate solution to remove theacid catalyst; the excess butyl alcohol and volatile butyl esters werethen separated out by evaporation under vacuum (pressure=0.1 mbar,temperature of vapours between 80-190° C.).

In the examples provided hereinafter, the following test methods wereadopted:

Determination of Bound Styrene and of the Polybutadiene Microstructure:

The method is based on the calculation of the ratios between theintensity of the bands attributable to styrene and the three Butadieneisomers (trans, vinyl and cis); the spectral areas used for theanalytical determination, relating to the cis, trans and 1,2 isomers ofbutadiene and styrene prove to be: 1018 and 937 cm⁻¹ for the transisomer, 934 and 887 cm⁻¹ for the 1,2 isomer (to be corrected due to theinterference of the styrene), 840 and 600 cm⁻¹ for the cis-isomer andfrom 715 to 680 cm⁻¹ for styrene. The measurement of the absorbances inthe maximum points and a knowledge of the extinction coefficient values,measured on standard polymers characterized via ¹H-NMR, allows thequantity of the various butadiene structures and the quantity of styreneto be calculated, by means of the Lambert-Beer law.

Determination of the Molecular Mass Distribution (MWD) (Limited toPolymers Obtained by Anionic Solution-Polymerization):

The determination of the molecular mass distribution is effected bymeans of gel permeation chromatography (GPC) also known as exclusionchromatography effected by passing a solution in THF of the polymer,object of the analysis, on a series of columns containing a solid phaseconsisting of crosslinked polystyrene with pores having variousdimensions.

Instrumental Configuration:

Chromatograph Agilent 1100

Solvent THF

Temperature 25° C.

PL-Gel Columns 10⁵-10⁵-10⁴-10³

RI detector Agilent 1100

The determination of the molecular mass is effected according to theUniversal Calibration method using the following values for k and α, inrelation to the quantity of styrene:

Styrene = 25% k = 0.000389 α = 0.693 Styrene = 30% k = 0.000368 α =0.693 Styrene = 40% k = 0.000338 α = 0.693

Determination of the Presence of Sequences and Polystyrene Blocks(Limited to Solution Polymers):

The method comprises a chemical degradation of styrene/butadienecopolymers by ozonolysis of the butadiene double bonds, followed byreduction and HPLC elution of the oligomers produced, in order to obtaina quantitative evaluation of the distribution of the styrene units inrandom and partially random SBRs. The possibility of having a doubleUV-MS detector allows the quantitative determination as % AREA from theUV plot and contemporaneously a control of the molecular weights of thespecies eluted, to be effected.

Determination of the Mooney Viscosity:

The determination of the Mooney viscosity (M_(L)) was effected at 100°C. with a rotor L and times (1+4) according to standard ASTM D1646.

Determination of the Tensile Properties (Ultimate Elongation, Elongationto Break, Moduli):

according to ASTM D 412 as previously described.

Determination of Tg and Tyre Tread Predictors (Commonly AcceptedPractice):

Glass transition temperature (Tg) was measured by dynamic mechanicalmeasurements (DMA). Tg is defined as the temperature corresponding tothe maximum of the curve of the damping factor (tan δ) versustemperature.

Tan δ measured at a temperature of 60° C., 5% deformation at a frequencyof 1 Hz was used as a predictor of rolling resistance (tan δ RR); thehigher Tan δ, the greater the rolling resistance. Tan δ measured at atemperature of 0° C., 0.1% deformation at a frequency of 0.1 Hz was usedas a predictor of the grip when braking or in bends presented by thetread blend (tan δ WG); the higher Tan δ, the better the grip. Themeasurement method is described in D. J. Schuring and S. Futamura,Rubber Chem. Technol. 63, 315 (1990).

As it is known, a lower tan δ at a temperature of 60° C. is desirablefor a tire tread to provide a tire with good rolling resistance while ahigh tan δ at a temperature of 0° C. is desirable for a tire tread toprovide a tire with good wet traction.

In the Examples, tan δ RR and tan δ WG values of compounds withtraditional extender oils were normalized to a value of 100 forcomparison purposes. The tan δ RR and tan δ WG values of compoundscomprising the elastomeric composition according to the presentinvention were reported relative to the normalized values of 100. Valueshigher than 100 therefore predict a performance improvement, i.e. alower tan δ RR or a higher tan δ WG with respect to compounds withtraditional extender oils.

Example 9—Comparison Preparation of SBR A

27.5% by weight of an extender oil of the RAE type was added to a baseelastomer consisting of a styrene-butadiene copolymer obtained byemulsion polymerization with a styrene content of 23.5%. Antioxidantswere added to the emulsion and then the emulsion was coagulated anddried according to the known art. The Mooney viscosity at 100° C. was45.

Example 10 Preparation of SBR B

27.5% by weight of the extender oil of the group a. of the vegetable oilderivatives according to the invention was added to a base elastomerconsisting of a styrene-butadiene copolymer obtained by emulsionpolymerization with a styrene content of 40%. Antioxidants were added tothe emulsion and then the emulsion was coagulated and dried according tothe known art. The Mooney viscosity at 100° C. was 44.

Example 11 Preparation of SBR C

27.5% by weight of an extender oil was added to a base elastomerconsisting of a styrene-butadiene copolymer obtained by emulsionpolymerization with a styrene content of 23.5%. The extender oilconsisted of 75% RAE mineral oil, the remaining 25% being a vegetableoil derivative belonging to the group a. according to the invention.Antioxidants were added to the emulsion and then the emulsion wascoagulated and dried according to the known art. The Mooney viscosity at100° C. was 42.

Example 12—Comparison Preparation of SBR D

27.5% by weight of an extender oil of the TDAE type was added to a baseelastomer consisting of a styrene-butadiene copolymer obtained byemulsion polymerization with a styrene content of 23.5%. Antioxidantswere added to the emulsion and then the emulsion was coagulated anddried according to the known art. The Mooney viscosity at 100° C. was39.

Example 13 Preparation of SBR E

27.5% by weight of an extender oil of the group a. of the vegetable oilderivatives according to the invention was added to a base elastomerconsisting of a styrene-butadiene copolymer obtained by solutionpolymerization with a styrene content of 35% by weight, vinyl unitcontent of the diene portion of 66%, with four radial arms and molecularweight of the arm equal to 320 kD, synthesized in a batch reactor, witha coupling efficiency of 80%. Antioxidants were added to the solution,the solvent was removed and then the solution was dried according to theknown art. The Mooney viscosity at 100° C. was 48.

Example 14—Comparison Preparation of SBR F

27.5% by weight of an extender oil of the TDAE type was added to a baseelastomer consisting of a styrene-butadiene copolymer obtained bysolution polymerization with a styrene content of 24% by weight, vinylunit content of the diene portion of 64%, with four radial arms andmolecular weight of the arm equal to 303 kD, synthesized in a batchreactor, with a coupling efficiency of 60%. The lower couplingefficiency was deliberately obtained in order to produce a polymerhaving a Mooney viscosity in the same range of that of SBR E (Example13). Antioxidants were added to the solution, the solvent was removedand then the solution was dried according to the known art. The Mooneyviscosity at 100° C. was 57. The characteristics of thestyrene-butadiene copolymers as prepared in Examples 9-14 are summarizedin Table 6.

TABLE 6 styrene-butadiene copolymers prepared in Examples 9-14. Extenderoil Base elastomer (% w of extender oil) Mooney Styrene Vinyl unitVegetable viscosity content content Oil at 100° C. Example Sample (%)(%) RAE TDAE Derivative a. (M_(L)) Comparison - 9 SBR A 23.5 15.5 100 —— 45 10 SBR B 40 16 — — 100 44 11 SBR C 23.5 15.5  75 —  25 42Comparison - 12 SBR D 23.5 15.5 — 100 — 39 13 SBR E 35 66 — — 100 48Comparison - 14 SBR F 24 64 — 100 — 57

Example 15

An elastomeric composition containing a RAE extender oil (Compound A) iscompared to an elastomeric composition according to the invention(Compound B). The two elastomeric compositions comprise emulsion SBR(prepared in Examples 9-comparison and 10) with a different styrenecontent and carbon black.

Table 7 shows the quantities by weight in the elastomeric compositionsin relation to one hundred parts of rubber (phr)

TABLE 7 quantities by weight (phr) in the elastomeric compositions ofExample 15 Material Compound A Compound B SBR A 100 — SBR B — 100 HAF330Carbon black 50 50 ZnO 3 3 Stearic Acid 1 1 Sulfur 1.75 1.75 SANTOCURENS TBBS 1 1 TBBS: N-Tertiarybutyl-2-benzothiazole-sulfenamide.

The tensile properties, vulcanization parameters (according to standardASTM D5289: M_(H), maximum torque; t₉₀, time in minutes needed to reach90% of maximum torque) and dynamic properties of the resulting compounds(damping factor correlated to the rolling resistance and wet grip) aresummarized in Table 8.

TABLE 8 M_(L) M_(H) t₉₀ E_((300%)) σ_(b) ε_(b) Tg Tan δ Tan δ compound(MU) Shore A (dN · m) (min) (MPa) (MPa) (%) (° C.) RR WG A 55 60 14 1514 27 510 −33 100 100 B 48 59 13 10 17 26 420 −34 105 101

The extension of the high styrene elastomeric base (SBR B) with thevegetable oil derivative a. according to Example 10 allows to prepareelastomeric compounds having a glass transition temperature comparablewith that of the reference compound extended with RAE.

By comparing compounds A and B, in addition to a general improvement ofmechanical properties and vulcanization parameters, an improvedperformance can be noted related to the predictiors commonly used forthe estimation of wet grip and rolling resistance.

Example 16

An elastomeric composition containing a TDAE extender oil (Compound D)is compared to an elastomeric composition according to the invention(Compound C). The two elastomeric compositions comprise emulsion SBR(prepared in Examples 12-comparison and 11) with the same styrenecontent and carbon black.

Table 9 shows the quantities by weight in the elastomeric compositionsin relation to one hundred parts of rubber (phr)

TABLE 9 quantities by weight (phr) in the elastomeric compositions ofExample 16 Material Compound C Compound D SBR C 100 — SBR D — 100 HAF330Carbon black 0 50 ZnO 3 3 Stearic Acid 1 1 Sulfur 1.75 1.75 SANTOCURE NSTBBS 1 1

The tensile properties, vulcanization parameters and dynamic propertiesof the resulting compounds are summarized in Table 10.

TABLE 10 M_(L) M_(H) t₉₀ E_((300%)) σ_(b) ε_(b) Tg Tan δ Tan δ compound(MU) Shore A (dN · m) (min) (MPa) (MPa) (%) (° C.) RR WG C 53 59 14 1315 27 500 −37 102 101 D 49 60 14 15 16 27 470 −36 100 100

The extension of the high styrene elastomeric base (SBR C) with thevegetable oil derivative a. according to Example 11 allows to prepareelastomeric compounds having a glass transition temperature comparablewith that of the reference compound extended with TDAE.

By comparing compounds C and D, an improved performance can be notedrelated to the predictiors commonly used for the estimation of wet gripand rolling resistance. The two elastomeric compounds show similarmechanical properties and vulcanization parameters.

Example 17

An elastomeric composition containing a RAE extender oil (Compound A) iscompared to an elastomeric composition according to the invention(Compound B). The two elastomeric compositions comprise emulsion SBR(prepared in Examples 9-comparison and 10) with a different styrenecontent and silica with coupling reaction in mixer.

Table 11 shows the quantities by weight in the elastomeric compositionsin relation to one hundred parts of rubber (phr).

TABLE 11 quantities by weight (phr) in the elastomeric compositions ofExample 17 Material Compound A1 Compound B1 SBR A 100 — SBR B — 100Ultrasil 7000 Silica 55 55 Si75 Silane 4.4 4.4 ZnO 2.7 2.7 ANOX HB 1.51.5 Stearic Acid 1.5 1.5 Sulfur 1 1 MBTS 1.3 1.3 DPG 1.5 1.5 Anox HBrefers to 2,2,4-trimethyl-1,2-dihydroquinoline polymer MBTS: 2-MercaptoBenzo Thiazole Sulphate DPG: diphenylguanidine.

The tensile properties, vulcanization parameters and dynamic propertiesof the resulting compounds are summarized in Table 12.

TABLE 12 M_(L) M_(H) t₉₀ E_((300%)) σ_(b) ε_(b) Tg Tan δ Tan δ compound(MU) Shore A (dN · m) (min) (MPa) (MPa) (%) (° C.) RR WG A1 52 63 15 512 31 580 −33 100 100 B1 55 63 14 13 13 26 510 −34 106 105

Elastomeric Compound B1 according to the invention has a glasstransition temperature comparable with that of the reference compoundextended with RAE (A1) and an improved performance related to thepredictors commonly used for the estimation of wet grip and rollingresistance.

The two elastomeric compounds show similar mechanical properties andvulcanization parameters.

Example 18

An elastomeric composition containing a RAE extender oil (Compound A) iscompared to an elastomeric composition according to the invention(Compound B). The two elastomeric compositions comprise emulsion SBR(prepared in Examples 9-comparison and 10) with a different styrenecontent, high cis polybutadiene content (cis-BR) and silica withcoupling reaction in mixer.

Table 13 shows the quantities by weight in the elastomeric compositionsin relation to one hundred parts of rubber (phr).

TABLE 13 quantities by weight (phr) in the elastomeric compositions ofExample 18 Material Compound A2 Compound B2 SBR A 75 — SBR B — 75 cis-BR25 25 Ultrasil 7000 Silica 55 55 Si75 Silane 4.4 4.4 ZnO 2.7 2.7 ANOX HB1.5 1.5 Stearic Acid 1.5 1.5 Sulfur 1 1 MBTS 1.3 1.3 DPG 1.5 1.5

The tensile properties, vulcanization parameters and dynamic propertiesof the resulting compounds are summarized in Table 14.

TABLE 14 M_(L) M_(H) t₉₀ E_((300%)) σ_(b) ε_(b) Tg Tan δ Tan δ compound(MU) Shore A (dN · m) (min) (MPa) (MPa) (%) (° C.) RR WG A2 76 65 19 411 26 530 −44 100 100 B2 69 63 18 5 12 23 500 −26 110 116

The different styrene content of the base elastomers (SBR A and B)generates a different thermodynamic compatibility with high 1.4-cispolybutadiene (cis-BR). This determine a modification of the glasstransition temperature of the compound with higher styrene content.Against comparable mechanical properties and vulcanization parameters,the resulting viscoelastic response favors the performance related tothe predictors commonly used for the estimation of wet grip and rollingresistance.

Example 19

An elastomeric composition containing a TDAE extender oil (Compound F)is compared to an elastomeric composition containing a vegetable oilderivative according to the invention (Compound E). The two elastomericcompositions comprise solution SBR (prepared in Examples 14-comparisonand 13) and silica with coupling reaction in mixer.

Table 15 shows the quantities by weight in the elastomeric compositionsin relation to one hundred parts of rubber (phr).

TABLE 15 quantities by weight (phr) in the elastomeric compositions ofExample 19 Material Compound E1 Compound F1 SBR E 100 — SBR F — 100Ultrasil 7000 Silica 55 55 Si75 Silane 4.4 4.4 ZnO 2.7 2.7 ANOX HB 1.51.5 Stearic Acid 1.5 1.5 Sulfur 1 1 MBTS 1.3 1.3 DPG 1.5 1.5

The tensile properties, vulcanization parameters and dynamic propertiesof the resulting compounds are summarized in Table 16.

TABLE 16 M_(L) M_(H) t₉₀ E_((300%)) σ_(b) ε_(b) Tg Tan δ Tan δ compound(MU) Shore A (dN · m) (min) (MPa) (MPa) (%) (° C.) RR WG E1 88 69 23 1612 17 280 −12 106 105 F1 96 66 22 14 11 16 260 −13 100 100

Rubber compound E1 has a glass transition temperature comparable withthat of the reference compound extended with TDAE (F1) and an improvedperformance related to the predictors commonly used for the estimationof wet grip and rolling resistance.

The two rubber compounds show similar mechanical properties andvulcanization parameters. The finding is of particular interest ifcompared to the lower Mooney torque of the elastomeric composition Ewith respect to F.

Example 20

An elastomeric composition containing a TDAE extender oil (Compound F)is compared to an elastomeric composition according to the invention(Compound E). The two elastomeric compositions comprise solution SBR(prepared in Examples 14-comparison and 13) with a different styrenecontent, high 1.4-cis polybutadiene content (cis-BR) and silica withcoupling reaction in mixer.

Table 17 shows the quantities by weight in the elastomeric compositionsin relation to one hundred parts of rubber (phr).

TABLE 17 quantities by weight (phr) in the elastomeric compositions ofExample 20 Material Compound E2 Compound F2 SBR E 75 — SBR F — 75 cis-BR25 25 Ultrasil 7000 Silica 55 55 Si75 Silane 4.4 4.4 ZnO 2.7 2.7 ANOX HB1.5 1.5 Stearic Acid 1.5 1.5 Sulfur 1 1 MBTS 1.3 1.3 DPG 1.5 1.5

The tensile properties, vulcanization parameters and dynamic propertiesof the resulting compounds are summarized in Table 18.

TABLE 18 M_(L) M_(H) t₉₀ E_((300%)) σ_(b) ε_(b) Tg Tan δ Tan δ compound(MU) Shore A (dN · m) (min) (MPa) (MPa) (%) (° C.) RR WG E2 79 68 23 810 18 330 −18 109 110 F2 84 63 21 6 8 15 310 −24 100 100

The different styrene content of the base elastomers (SBR E and F)generates a different thermodynamic compatibility with high 1.4-cispolybutadiene (cis-BR). This determine a different viscoelastic responseof the compound with higher styrene content in the region of the glasstransition temperature. This response results, in parallel with animprovement of mechanical properties and vulcanization parameters, in asuperior performance related to the predictors commonly used for theestimation of wet grip and rolling resistance. The finding is ofparticular interest if compared to the lower Mooney torque of theelastomeric composition E with respect to F.

As can be noted comparing Tables 8, 10, 12, 14, 16 and 18, the extenderoil according to the invention allows to obtain elastomeric compositionswith:

-   -   comparable mechanical properties (even improved, see Table 8),    -   comparable vulcanization parameters,    -   improved performances linked to the predictors commonly used for        the estimation of wet grip and, surprisingly, of rolling        resistance        when compared to traditionally oil extended elastomeric        compositions having similar Tg values. This is evident even when        they represent a minority component in a mixture with mineral        extender oils (Table 10).

The invention claimed is:
 1. Elastomer composition comprising at leastone elastomer and at least one vegetable oil derivative selected fromone or more of: a. mixture of triglycerides comprising one or more ofthe following oligomeric structures:R₄—[O—C(O)—R₁—C(O)—O—CH₂—CH(OR₂)—CH₂]_(n)—O—R₃ wherein R₁ is selectedfrom C₂-C₂₂ alkylenes, R₂ is selected from one or more of the followinggroups consisting of C₆-C₂₄ dicarboxylic acid residues and C₆-C₂₄monocarboxylic acid residues, R₃ is selected from one or more of thefollowing groups consisting of H, C₆-C₂₄ dicarboxylic acid residues andC₆-C₂₄ monocarboxylic acid residues, R₄ is an alkyl group, n is aninteger greater than or equal to 2, said C₆-C₂₄ dicarboxylic acidresidues of R₂ and R₃ being esterified with monoalcohols and saidmixture of triglycerides having a Numerical Average Molecular Weight(Mn) of between 800 and 10,000; b. esters of polyols with at least amonocarboxylic acid and at least a dicarboxylic acid, the said estersbeing other than triglycerides.
 2. Elastomer composition according toclaim 1, in which said at least one elastomer is a natural rubber or asynthetic rubber.
 3. Elastomer composition according to claim 2, inwhich said at least one elastomer is a synthetic rubber selected fromthe group consisting of diene-based rubbers, thermoplastic elastomers,nitrile rubbers, acrylonitrile-butadiene copolymers (NBR) andstyrene-isoprene-styrene (SIS) polar rubbers.
 4. Elastomer compositionaccording to claim 3, in which said at least one elastomer is adiene-based rubber.
 5. Elastomer composition according to claim 4, inwhich said diene-based rubber is a vinylarene-conjugated dienecopolymer.
 6. Elastomer composition according to claim 5, in which saidvinylarene-conjugated diene copolymer is a styrene-1,3-butadiene randomcopolymer.
 7. Elastomer composition according to claim 6, in which saidstyrene-1,3-butadiene random copolymer has a styrene content from 15 to50% by weight.
 8. Elastomer composition according to claim 6, in whichsaid styrene-1,3-butadiene random copolymer has a vinyl unit contentfrom 10 to 80% with respect to the diene content.
 9. Elastomercomposition according to claim 6, in which said styrene-1,3-butadienerandom copolymer is obtained from solution or as emulsion.
 10. Elastomercomposition according to claim 1, wherein the R₁ group of the vegetableoil derivatives of type (a) is C₆-C₁₁ alkylene.
 11. Elastomercomposition according to claim 1, wherein the C₆-C₂₄ dicarboxylic acidresidues of R₂ and R₃ are suberic acid, azelaic acid and brassylic acidand their mixtures.
 12. Elastomer composition according to claim 1,wherein the R₄ group of the vegetable oil derivatives of type (a) is aC₁-C₁₂ alkyl group.
 13. Elastomer composition according to claim 1, inwhich the vegetable oil derivatives of type (a) comprise dimer and/ortrimer esters of triglycerides containing C₆-C₂₄ dicarboxylic acidsresidues.
 14. Elastomer composition according to claim 1, in which thevegetable oil derivative is of type (a).
 15. Elastomer compositionaccording to claim 1, in which the vegetable oil derivative is used in amixture with mineral and/or natural oils.
 16. Elastomer compositionaccording to claim 15, wherein said mixtures contain 15-45% by weight ofvegetable oil derivatives.
 17. Elastomer composition according to claim1 comprising one or more of the following ingredients: vulcanisationagents, vulcanisation accelerators, activators, retardants, organicacids, antioxidants, fillers, reinforcing materials, processcoadjuvants.
 18. Elastomer composition according to claim 17 in whichthe reinforcing materials belong to the group comprising carbon black,silicas and biofillers from renewable sources.
 19. Raw elastomericcomposition comprising: (A1) from 30 to 100% by weight of avinylarene-conjugated diene random elastomeric copolymer, (A2) from 0 to70% by weight of one or more diene rubbers, the total amount ofelastomers (A1)+(A2) being equal to 100, and (B) from 10 to 150 phr ofsilica or carbon black or mixtures thereof; (C) from 10 to 100 phr, ofat least one vegetable oil derivative selected from one or more of: a.mixture of triglycerides comprising one or more of the followingoligomeric structures:R₄—[O—C(O)—R₁—C(O)—O—CH₂—CH(OR₂)—CH₂]_(n)—O—R₃ wherein R₁ is selectedfrom C₂-C₂₂ alkylenes, R₂ is selected from one or more of the followinggroups consisting of C₆-C₂₄ dicarboxylic acid residues and C₆-C₂₄monocarboxylic acid residues, R₃ is selected from one or more of thefollowing groups consisting of H, C₆-C₂₄ dicarboxylic acid residues andC₆-C₂₄ monocarboxylic acid residues, R₄ is an alkyl group, n is aninteger greater than or equal to 2, said C₆-C₂₄ dicarboxylic acidresidues of R₂ and R₃ being esterified with monoalcohols and saidmixture of triglycerides having a Numerical Average Molecular Weight(Mn) of between 800 and 10,000, b. triglycerides of one or more longchain carboxylic acids including at least one carboxylic acid containingadjacent hydroxyl groups, c. esters of polyols with at least amonocarboxylic acid and at least a dicarboxylic acid, the said estersbeing other than triglycerides, (D) from 0.1 to 20 phr of a couplingagent based on silane; (E) from 0.1 to 10 phr of a vulcanizing agent.20. Rubber compounds prepared from the elastomeric composition accordingto claim
 1. 21. Tyre tread comprising the rubber compound according toclaim
 20. 22. A mixture of elastomers of natural and/or synthetic originwith one or more derivatives of vegetable oils as an extender oil beingselected from one or more of: a. mixture of triglycerides comprising oneor more of the following oligomeric structures:R₄—[O—C(O)—R₁—C(O)—O—CH₂—CH(OR₂)—CH₂]_(n)—O—R₃ wherein R₁ is selectedfrom C₂-C₂₂ alkylenes, R₂ is selected from one or more of the followinggroups consisting of C₆-C₂₄ dicarboxylic acid residues and C₆-C₂₄monocarboxylic acid residues, R₃ is selected from one or more of thefollowing groups consisting of H, C₆-C₂₄ dicarboxylic acid residues andC₆-C₂₄ monocarboxylic acid residues, R₄ is an alkyl group, n is aninteger greater than or equal to 2, said C₆-C₂₄ dicarboxylic acidresidues of R₂ and R₃ being esterified with monoalcohols and saidmixture of triglycerides having a Numerical Average Molecular Weight(Mn) of between 800 and 10,000; b. esters of polyols with at least amonocarboxylic acid and at least a dicarboxylic acid, the said estersbeing other than triglycerides.
 23. A tyre comprising an elastomercomposition which comprises at least one elastomer and at least onevegetable oil derivative selected from one or more of: a. mixture oftriglycerides comprising one or more of the following oligomericstructures:R₄—[O—C(O)—R₁—C(O)—O—CH₂—CH(OR₂)—CH₂]_(n)—O—R₃ wherein R₁ is selectedfrom C₂-C₂₂ alkylenes, R₂ is selected from one or more of the followinggroups consisting of C₆-C₂₄ dicarboxylic acid residues and C₆-C₂₄monocarboxylic acid residues, R₃ is selected from one or more of thefollowing groups consisting of H, C₆-C₂₄ dicarboxylic acid residues andC₆-C₂₄ monocarboxylic acid residues, R₄ is an alkyl group, n is aninteger greater than or equal to 2, said C₆-C₂₄ dicarboxylic acidresidues of R₂ and R₃ being esterified with monoalcohols and saidmixture of triglycerides having a Numerical Average Molecular Weight(Mn) of between 800 and 10,000; b. triglycerides of one or more longchain carboxylic acids including at least one carboxylic acid containingadjacent hydroxyl groups, c. esters of polyols with at least amonocarboxylic acid and at least a dicarboxylic acid, the said estersbeing other than triglycerides.
 24. Elastomer compositions containingsilicas and esters of polyols with at least a monocarboxylic acid and atleast a dicarboxylic acid, the said esters being derived from vegetableoils other than triglycerides, as compatibilising agents.